1. Field of the Invention
The present invention relates to a scroll-type compressor for a fuel cell. More particularly, the present invention relates to a scroll-type compressor that makes an exhausted gas from the fuel cell flow in again to additionally support the driving power of the compressor.
2. Description of the Related Art
Recently, a fuel cell has begun to attract attention as a drive source for electric cars. In a fuel cell, oxygen and hydrogen, compressed in advance by a compressor, are made to react to generate electricity. Water produced in the reaction, and a gas from which oxygen and hydrogen have been consumed is exhausted.
In most cases, the gas exhausted from the fuel cell maintains a state of high pressure. A scroll-type compressor equipped with a regeneration mechanism, which utilizes the energy produced by the expansion of the exhausted gas in the state of high pressure to additionally support the driving power of the compressor, has been disclosed in Japanese Unexamined Patent Publication (Kokai) No.2000-156237.
FIG. 4 is an axial cross-sectional view of the scroll-type compressor 100 with a regeneration mechanism. A housing 101 is the outer shell of the scroll-type compressor 100. On a discharge side inner surface 102 of the housing 101, a fixed scroll for compression 103 is erected in the direction of the motor. On a motor-side inner surface 104, which opposes the discharge side inner surface 102, a fixed scroll for expansion 105 is erected in the direction of discharge. Between these two fixed scrolls, a movable plate 106, equipped with a shaft insertion portion 114 that opens toward the motor side in the center of the inner circumferential side, is provided.
On the inner circumferential side of the shaft insertion portion 114, a bearing 115 to which a lubricant has been applied and two ring-seal members 117 that enclose the lubricant are provided. Moreover, into the further inner circumferential side of the bearing 115, a crank-shaped drive shaft 110 is rotatably inserted.
On the discharge side surface of the movable plate 106, a movable scroll for compression 107 is erected and on the motor-side surface of the movable plate 106, a movable scroll for expansion 108 is erected. A compression chamber 111 is defined by the fixed scroll for compression 103 and the movable scroll for compression 107. Moreover, a suction port 120 is formed on the outermost circumferential portion of the compression chamber 111 and a discharge port 121 is formed in the central portion of the inner circumferential side thereof, respectively.
On the other hand, an expansion chamber 112 is defined between the fixed scroll for expansion 105 and the movable scroll for expansion 108. Moreover, an inflow port 130 is formed in the central portion of the inner circumferential side of the expansion chamber 112 and an outflow port 131 is formed on the outermost circumferential portion thereof, respectively.
On the outer circumferential portion of the movable plate 106, a self-rotation preventing shaft 113 that prevents the self-rotation of the movable plate 106 is provided.
When the motor causes the drive shaft 110 to rotate and the movable scroll for compression 107 revolves, the air to be supplied to the fuel cell is sucked into the compression chamber 111 through the suction port 120 and moves toward the central side of the fixed scroll for compression 103 while being compressed. The compressed air is supplied to the fuel cell through the discharge port 121. The air, the oxygen of which has been consumed in the reaction in the fuel cell, is exhausted from the fuel cell as an exhaust gas. Then the exhaust gas flows again into the inside of the expansion chamber 112 through the inflow port 130 and moves toward the outer circumferential side of the fixed scroll for expansion 105 while expanding. At this time, the expansion energy of the exhaust gas is converted into the drive energy of the drive shaft 110. The expanded exhaust gas is exhausted to the outside of the compressor 100 through the outflow port 131.
In such a conventional scroll-type compressor for a fuel cell, however, the exhaust gas of the fuel cell directly hits the seal member 117 when the exhaust gas flows into the inside of the expansion chamber 112 through the inflow port 130. The exhaust gas contains water produced in the reaction in the fuel cell. On the other hand, the seal member 117 is provided in order to prevent the leakage of the lubricant from the bearing 115, as described above. However, since the physical characteristic, such as the viscosity, of water differs from lubricant, it is difficult to prevent the water contained in the exhaust gas from entering by the seal member 117. Therefore, in the conventional scroll-type compressor the lubricant is degraded due to the water that has entered the bearing 115.
In this case, it seems to be possible to suppress the degradation of lubricant by decreasing the flow speed of the exhaust gas, that is, by decreasing the flow rate, to prevent water from entering. But, if the flow rate is reduced, the effect to additionally support the driving power of the compressor with the aid of the expansion energy of the compressed exhaust gas is also reduced.
The present invention has been developed and completed with the above-mentioned problems being taken into account, and the object is to provide a scroll-type compressor for a fuel cell that can prevent the water contained in the exhaust gas from entering the inside of the bearing and prevent the degradation of lubricant without decreasing the flow rate of the exhaust gas.
In order to solve the above-mentioned problems, the scroll-type compressor for a fuel cell of the present invention comprises: a fixed scroll for compression; a movable scroll for compression that defines a compression chamber, between the movable scroll for compression and the fixed scroll for compression, in which a gas sucked from the outer circumferential side is compressed by moving the gas in the direction of the inner circumference; a movable plate that has the movable scroll for compression erected on a first surface thereof and a cup-shaped cylindrical shaft insertion portion, which opens toward a second surface reverse to the first surface near the center and into which a drive shaft is inserted; a bearing that is provided inside the shaft insertion portion and supports the drive shaft with a lubricant therein; a fixed scroll for expansion provided in such a way as to oppose the second surface of the movable plate; a movable scroll for expansion that is erected on the second surface of the movable plate and defines an expansion chamber, between the movable scroll for expansion and the fixed scroll for expansion, in which the gas, which has flowed in through the inflow port formed near the center of the inner circumferential side, is expanded by moving the gas in the direction of the outer circumference; wherein the compressor also comprises a seal member that prevent the leakage of the lubricant through the opening end of the shaft insertion portion, and an obstruction member provided between the seal member and the inflow port to prevent water, contained in the gas, from entering the bearing within the shaft insertion portion by changing the flow of the gas, containing the water, that flows in through the inflow port.
In other words, the scroll-type compressor for the fuel cell of the present invention provides the obstruction member, that prevents the water contained in the exhaust gas from entering the bearing, in addition to the seal member. Conventionally, the exhaust gas flowing in through the inflow port directly hits the seal member and the water contained in the gas enters the inside of the bearing. In other words, no obstacle exists, that blocks the passage of the exhaust gas, between the inflow port and the seal member.
The scroll-type compressor for a fuel cell of the present invention newly provides the obstruction member that blocks the passage of the exhaust gas. If the obstruction member is provided, the flowing direction of the exhaust gas can be changed and it is possible to prevent the exhaust gas flow from directly hitting the seal member. In this way, it is possible to prevent the water contained in the exhaust gas from entering the inside of the bearing and to prevent the lubricant from degrading.
The present invention may be more fully understood from the description of the preferred embodiments of the invention set forth below, together with the accompanying drawings.